Linerless labels with pressure sensitive adhesive on one face, and a release coating on the other, are becoming increasingly more popular because they have a number of advantages over conventional lined labels, including the absence of the need to dispose of a liner when the labels are dispensed. However linerless labels pose substantial challenges in developing efficient procedures and equipment for dispensing them. When linerless labels are being dispensed care must be taken to avoid excess unwind of the labels since it can be difficult to properly rewind the linerless labels, and there is always the danger of the exposed pressure sensitive adhesive sticking to components of, or structures adjacent, the unwind apparatus. Also, care must be taken not to scuff the non-adhesive face of the labels, and to properly guide the labels for dispensing.
Another significant problem in the dispensing of linerless labels is sticking of the labels to dispensing apparatus components for separating the labels along their perforations. When a label sticks to the tear surface, lifting the leading edge to start the next label is very difficult, and can unreasonably increase the time required to manually dispense the labels. Also, where blades or like components are used as a force concentrating structure to facilitate tearing of the labels along the perforation lines, the force concentrating structures must be cleaned often to prevent a build up of adhesive.
According to the present invention a simple apparatus is provided which overcomes all of the problems set forth above with respect to the dispensing of linerless labels. That is, the apparatus according to the present invention provides a brake drag effect to prevent excess label unwind, ensures consistent wrap and guiding of the labels with no scuffing of the non-adhesive face as the labels are dispensed from a roll, provides force concentration on the perforation lines without frequent build up of adhesive on structural components, and allows ready access to the free end of the leading label so that dispensing may be accomplished quickly and efficiently. Despite having all of these advantageous features, solving problems existing in the art, the invention is extremely simple, making it relatively inexpensive to construct and utilize and easy to use and repair. Also, the apparatus according to the invention may be used in a novel method for dispensing the labels by facilitating tear-off of the leading label of the web.
According to one aspect of the present invention apparatus for manually dispensing linerless labels having a pressure sensitive adhesive face and a non-adhesive face is provided. The apparatus comprises the following elements: Means for mounting for ready dispensing a roll of linerless labels having the adhesive surface thereof as an inner surface of the labels on the roll. Means for providing label unwind tensioning of the roll by providing a brake drag effect to prevent excess label unwind. Means for straightening of the labels, and no scuffing of the non-adhesive face, as the labels are dispensed from the roll. And, tear surface means including a first surface portion having low adhesion to the adhesive of the labels, and a non-stick second surface portion having much lower adhesion to the adhesive of the labels than the first surface, the second surface located further from the means for mounting the roll, along a path of movement of the labels, than the first surface. The second surface portion comprises metal covered with material selected from the group consisting essentially of non-stick varnishes (including silicone epoxy coatings), polypropylene baked enamels, polytetrafluoroethylene (PTF) coatings, and PTF strips.
The tear surface preferably comprises an arcuate surface, such as the exterior surface of a metal cylinder or tube. The first surface portion comprises a smooth, ribbed, patterned, or coarse metal surface exterior portion of the cylinder or tube, while the second surface portion comprises the non-stick coating on the metal surface described above. The differential adhesion between the first and second surface portions to the label web adhesive allows ready force concentration on a perforation when a perforation between leading and trailing labels substantially overlies the second surface portion, while a part of the trailing label securely adhesively engages the first surface portion. Application of a force to the leading label then causes detachment of the leading and trailing labels along the perforation, and allows the perforation-defined edge of the trailing label to be readily accessible for the next dispensing action.
The means for straightening the labels, and no scuffing of the non-adhesive surface, as the labels are dispensed from the roll preferably comprises a tree-rotating guide roll having a lubricated exterior surface for engaging the non-adhesive face of the labels. The lubricated exterior surface may comprise high molecular weight polyethylene (that is the roller may be constructed of that material), or PTF (e.g. the exterior surface of the roller can be coated with Teflon.RTM.).
The means for mounting the roll for ready dispensing preferably comprises a stationary shaft received within a hollow core of the roll of labels, and having flattened ends which are mounted in a support structure. The means for providing label unwind tensioning may comprise a material disposed between the shaft and the core retarding, though allowing, rotation of the roll about the shaft when an unwind force is applied to the labels. The material disposed between the shaft and the core may comprise a foam core, for example a foam core having a polygon (e.g. square) cross sectional shape. The foam core may have a longitudinal slit allowing ready removal from the shaft for replacement if it wears out, or for cleaning or repair.
A stationary frame having side walls with slots formed therein for receipt of the shaft may also mount the guide roller for rotation about a substantially horizontal axis. The axis of rotation of the guide roller is parallel to the shaft, and is located, typically, below both the shaft and the second surface portion of the tear means.
A method of manually dispensing labels from an elongated web of labels in a roll configuration, having perforations spaced along the length of the web, perpendicular to the dimension of elongation of the web, may also be provided. The web has a pressure sensitive adhesive face, and a non-adhesive face. The method utilizes a tear surface having a non-stick portion (a plasma coating, or silicone epoxy coatings, polypropylene baked enamels, PTF coatings, and PTF strips) which does not adhere to the adhesive face, and a low adhesion portion that is capable of adhesion to the adhesive face to exert a holding force on a label greater than the force necessary to separate the label along a perforation, while still allowing release of the adhesive face therefrom. The method comprises the following steps: (a) Mounting the roll for rotation about an axis of rotation, with a brake drag effect to prevent excess label unwind. (b) Passing the web around a free-rotating roller with the non-adhesive face of the web in contact with the exterior surface of the free-rotating roller. (c) Bringing the leading label perforation of the web into a position substantially overlying the non-stick portion of the tear surface, while the next trailing label adhesive face engages the low-adhesion portion of the tear surface. And, (d) applying a force to the leading label of the web generally perpendicular to the leading perforation (or cause it to be torn angularly across the face of the web) to cause detachment of the leading label from the web at the leading label perforation so that the next trailing label becomes the leading label, and so that the leading edge thereof overlies the non-stick portion. The tear surface is typically arcuate, and step (d) is typically practiced by applying a pulling or snapping force to the web that is generally tangent to the arcuate surface at the perforation.
It is the primary object of the present invention to provide a simple yet extremely effective apparatus and method for dispensing linerless labels. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.